Is there any real difference between the computer install and running off the zip file? Faster, slower, less memory? General pros or cons?

There's no functional difference, it's just that some people prefer the one, others the other way of installing.

any chance of getting a portable version for linux?

Not any time soon. I spent a couple of days on that, but with the amount of 3rd party libraries we use, it's just too big a task for me, in addition to the other stuff I try to do. If someone volunteers to look into it, I'd be happy to share my notes, of course.